1. Technical Field
The present disclosure relates to a measuring device assembly and method for fabricating measuring device assemblies and, more particularly, to measuring device assemblies having zero/span adjustable linkage movements (e.g., zero/span adjustable four-bar linkage movements).
2. Background Art
Measuring devices, such as instruments and gauges used for measuring temperature and pressure, have innumerable uses in industry. For example, pressure gauges to measure the pressure of process media are well known. Pressure gauges are useful in a myriad of different environments for commercial and industrial applications. Typically, pressure gauges measure pressure and provide an indication of the value. Pressure values are usually displayed in analog form (e.g., by a pointer) or in digital form (e.g., by an electronic readout).
Price competition between the various measuring device manufacturers is a factor in the marketplace. Therefore, a savings in the cost of material, labor and the like by a manufacturer can have a significant effect on that manufacturer's sales, market share and margins. Therefore, a constant need exists among these manufacturers to develop more cost effective manufacturing techniques.
In general, forms of measuring devices of the suspended movement type are disclosed, for example, in U.S. Pat. Nos. 4,055,085; 4,237,738; 4,246,796; 4,444,057 and 6,295,876, each incorporated herein by reference in their entireties. For example, U.S. Pat. No. 4,055,085 (the “'085 patent”) discloses a pressure gauge or the like in which the amplifier movement is supported on the free end of a condition responsive element (e.g., a Bourdon tube or the like) for floating conjointly with displacement of the element end. An actuator extends into the motion path of the floating amplifier to define a pivot axis for a hinged gear sector arm of the amplifier. In pivoting about the actuator axis, the sector arm operably drives a rotatable output shaft supporting a pointer or indicator or the like opposite a graduated dial face.
The '085 patent also discloses designs for suspended movement measuring devices having span adjustment. In general, span adjustment is for effecting pointer or indicator travel coincident with the dial span encountered by the measuring device on being subject to a full range of condition changes (e.g., pressures) through which it is intended to operate. Typically, this span adjustment system/method utilizes a square socket with a tapered screw, and the suspended movement measuring device may be calibrated with the dial in place. However, this span adjustment system/method adds costly machining operations to the socket and/or to the measuring device (e.g., mounting features for the dial, a threaded hole for a tapered screw, alignment/mounting groove for an actuator). In addition, this system/method is typically only used on brass systems due to the complexity of the parts, as stainless steel parts, for example, would generally be too expensive to utilize in a similar or like design.
Another existing system/method for suspended movement measuring devices having span adjustment typically includes a wire and block assembly. In general, this assembly is difficult to adjust, and is typically susceptible to shifts in shock, due to the construction of the assembly, for example. In addition, generally the dial of the measuring device must be removed in order to calibrate the measuring device, which typically makes calibration difficult. For example, with no dial, an operator cannot see the measurement tick marks. In general, this span adjustment system/method for suspended movement measuring devices cannot be automated.
Another existing system/method for suspended movement measuring devices having span adjustment is disclosed and described in U.S. Pat. No. 7,503,222, the entire contents of which is herein incorporated by reference. However, suspended movement measuring devices and/or measuring devices that utilize gear movements or the like generally require a large number of components, and are not rugged under certain shock and/or vibration conditions. In general, measuring devices having a linkage movement are more durable under such conditions.
One example of a measuring device having a linkage movement is disclosed and described in U.S. Pat. No. 5,349,866, the entire contents of which is herein incorporated by reference. However, such existing measuring devices that utilize linkage mechanisms to amplify angular movement accomplish span adjustment in such a way that it also affects the linearity of the measuring devices (e.g., the linear relationship between input and output angles).
Thus, despite efforts to date, a need remains for cost effective and efficient systems/methods that provide for measuring device assemblies having zero/span adjustable linkage movements (e.g., zero/span adjustable four-bar linkage movements). In addition, a need remains for systems/methods that provide for measuring device assemblies having zero/span adjustable linkage movements where the zero/span adjustable linkage movements do not adversely affect linearity of the measuring device assemblies, and where the measuring device assemblies are rugged and able to withstand certain extreme shock and/or vibration conditions.
These and other inefficiencies and opportunities for improvement are addressed and/or overcome by the systems and methods of the present disclosure.